Method and apparatus for transmitting/receiving multiple codewords in SC-FDMA system

Abstract

The present invention relates a method and apparatus for transmitting/receiving data using multiple codewords in a communication system using SC-FDMA (single carrier frequency division multiple access). A transmitter generates the multiple codewords for user data and transmits the generated multiple codewords. A receiver receives the multiple codewords and sequentially performs decoding and SIC (successive interference cancellation) on the received multiple codewords. Therefore, this structure can minimize a PAPR (peak to average power ratio) and considerably reduces interference between symbols in a frequency selective fading environment.

What is claimed is: 
     
       1. A communication methodof transmitting symbols in a transmitter, the method comprising:
 preparing a plurality of sub-streams includinggenerating a first sub-streamstream and a second sub-streamstream; 
 independently performing first channel coding on each of the first stream to generate a first channel coded stream and performing second channel coding on the second sub-streams stream to generate a second channel coded stream, wherein the first channel coding and the second channel coding are performed according to different coding schemes; 
 mapping the first and second channel coded sub-streams streams to modulation symbols, wherein different channel coded sub-streams streams are mapped to different modulation symbols; 
 generating single carrier frequency division multiple access (SC-FDMA) symbols from the modulation symbols, one of the SC-FDMA symbols being generated by using at least a part of the modulation symbols from the first sub-stream channel coded stream and a part of the modulation symbols from the second sub-stream channel coded stream; and 
 transmitting the SC-FDMA symbols to a receiver. 
 
     
     
       2. The method of  claim 1 , wherein generating the SC-FDMA symbols comprises:
 transforming the modulation symbols; 
 mapping the transformed symbols to subcarriers; and 
 generating the SC-FDMA symbols from the symbols mapped to the subcarriers. 
 
     
     
       3. The method of  claim 1 , wherein a transfer rate of the first sub-stream and a transfer rate of the second sub-stream are differently determined. 
     
     
       4. The method of claim  3  1, further comprising receiving an offset for determining the transfer rate of the first sub-stream and the transfer rate of the second sub-stream from the receiver wherein a coding rate of the first channel coding is different from a coding rate of the second channel coding. 
     
     
       5. The method of  claim 1 , further comprising receiving feedback information from the receiver; and
 determining transfer rates of the sub-streams coding rates of the first channel coding and the second channel coding based on the feedback information. 
 
     
     
       6. A method of receiving a signal in a receiver, the method comprising: receiving single carrier frequency division multiple access (SC-FDMA) symbols from a transmitter; and
 extracting a plurality of sub-streams including a first sub-stream and a second sub-stream from the SC-FDMA symbols,   wherein the SC-FDMA symbols are generated, by the transmitter, by independently performing channel coding on each of the first and second sub-streams, mapping the channel coded sub-streams to modulation symbols, generating the SC-FDMA symbols from the modulation symbols,   wherein different channel coded sub-streams are mapped to different modulation symbols, and wherein one of the SC-FDMA symbols are generated by using at least part of the modulation symbols from the first sub-stream and part of the modulation symbols from the second sub-stream.   
     
     
       7. The method of  claim 6 , wherein the modulation symbols are transformed, the transformed symbols are mapped to subcarriers, and the SC-FDMA symbols are generated from the symbols mapped to the subcarriers, by the transmitter. 
     
     
       8. The method of  claim 6 , wherein a transfer rate of the first sub-stream and a transfer rate of the second sub-stream are differently determined. 
     
     
       9. The method of  claim 8 , further comprising transmitting an offset for determining the transfer rate of the first sub-stream and the transfer rate of the second sub-stream. 
     
     
       10. The method of  claim 6 , further comprising transmitting feedback information for determining transfer rates of the sub-streams to the transmitter. 
     
     
       11. A transmitter comprising:
 a demultiplexer configured to prepare a plurality of sub-streams including a first sub-stream and a second sub-stream;   a plurality of encoders configured to independently perform channel coding on each of the first and second sub-streams;   a mapper configured to map the channel coded sub-streams to modulation symbols, wherein different channel coded sub-streams are mapped to different modulation symbols; and   a generator configured to generate single carrier frequency division multiple access (SC-FDMA) symbols, to be transmitted to a receiver, from the modulation symbols, one of the SC-FDMA symbols being generated by using at least part of the modulation symbols from the first sub-stream and part of the modulation symbols from the second sub-stream.   
     
     
       12. The transmitter of  claim 11 , wherein the generator comprises:
 a first transformer configured to transform the modulation symbols;   a subcarrier mapper configured to map the transformed symbols to subcarriers; and   a second transformer configured to generate the SC-FDMA symbols from the symbols mapped to the subcarriers.   
     
     
       13. The transmitter of  claim 11 , wherein a transfer rate of the first sub-stream and a transfer rate of the second sub-stream are differently determined. 
     
     
       14. The transmitter of  claim 13 , further comprising a rate controller configured to receive an offset for determining the transfer rate of the first sub-stream and the transfer rate of the second sub-stream from the receiver. 
     
     
       15. The transmitter of  claim 11 , further comprising a rate controller configured to receive feedback information from the receiver, and determine transfer rates of the sub-streams based on the feedback information. 
     
     
       16. A receiver comprising:
 a receiver configured to receive single carrier frequency division multiple access (SC-FDMA) symbols from a transmitter; and   a decoder configured to extract a plurality of sub-streams including a first sub-stream and a second sub-stream from the SC-FDMA symbols,   wherein the SC-FDMA symbols are generated, by the transmitter, by independently performing channel coding on each of the first and second sub-streams, mapping the channel coded sub-streams to modulation symbols, generating the SC-FDMA symbols from the modulation symbols,   wherein different channel coded sub-streams are mapped to different modulation symbols, and   wherein one of the SC-FDMA symbols are generated by using at least part of the modulation symbols from the first sub-stream and part of the modulation symbols from the second sub-stream.   
     
     
       17. The receiver of  claim 16 , wherein the modulation symbols are transformed, the transformed symbols are mapped to subcarriers, and the SC-FDMA symbols are generated from the symbols mapped to the subcarriers, by the transmitter. 
     
     
       18. The receiver of  claim 16 , wherein a transfer rate of the first sub-stream and a transfer rate of the second sub-stream are differently determined. 
     
     
       19. The receiver of  claim 18 , further comprising an information generator configured to transmit an offset for determining the transfer rate of the first sub-stream and the transfer rate of the second sub-stream. 
     
     
       20. The receiver of  claim 16 , further comprising an information generator configured to transmit feedback information for determining transfer rates of the sub-streams to the transmitter. 
     
     
       21. The communication method of claim 1, wherein the one of the SC-FDMA symbols is transmitted from a single antenna. 
     
     
       22. A communication apparatus, comprising:
 a circuitry configured to:
 cause the communication apparatus to generate a first stream and a second stream; 
 cause the communication apparatus to perform first channel coding on the first stream to generate a first channel coded stream and perform second channel coding on the second stream to generate a second channel coded stream, wherein the first channel coding and the second channel coding are performed according to different coding schemes; 
 cause the communication apparatus to map the first and second channel coded streams to modulation symbols, wherein different channel coded streams are mapped to different modulation symbols; 
 cause the communication apparatus to generate single carrier frequency division multiple access (SC-FDMA) symbols from the modulation symbols, one of the SC-FDMA symbols being generated by using at least a part of the modulation symbols from the first channel coded stream and a part of the modulation symbols from the second channel coded stream; and 
 cause the communication apparatus to transmit the SC-FDMA symbols to a receiver. 
   
     
     
       23. The communication apparatus of claim 22, wherein the circuitry is configured to, when generating the SC-FDMA symbols:
 cause the communication apparatus to map the modulation symbols to subcarriers; and   cause the communication apparatus to generate the SC-FDMA symbols from the subcarriers.   
     
     
       24. The communication apparatus of claim 22, wherein a coding rate of the first channel coding is different from a coding rate of the second channel coding. 
     
     
       25. The communication apparatus of claim 22, wherein the circuitry is further configured to cause the communication apparatus to receive feedback information from the receiver; and
 determine coding rates of the first channel coding and the second channel coding based on the feedback information.   
     
     
       26. The communication apparatus of claim 22, wherein the one of the SC-FDMA symbols is transmitted from a single antenna. 
     
     
       27. A communication apparatus, comprising:
 a circuitry configured to:
 cause the communication apparatus to receive single carrier frequency division multiple access (SC-FDMA) symbols from a transmitter; 
 cause the communication apparatus to generate modulation symbols from the SC-FDMA symbols; 
 cause the communication apparatus to generate a first channel coded stream and a second channel coded stream from the modulation symbols, wherein at least a part of the first channel coded stream and at least a part of the second channel coded stream are generated from one of the SC-FDMA symbols; 
 and cause the communication apparatus to perform first channel decoding on the first channel coded stream to generate a first stream and perform second channel decoding on the second channel coded stream to generate a second stream, wherein the first channel decoding and the second channel decoding are performed according to different decoding schemes. 
   
     
     
       28. The communication apparatus of claim 27, wherein a coding rate of the first channel decoding is different from a coding rate of the second channel decoding. 
     
     
       29. The communication apparatus of claim 27, wherein the circuitry is further configured to:
 cause the communication apparatus to generate feedback information based on the first channel decoding and the second channel decoding; and   cause the communication apparatus to transmit the feedback information to the transmitter.   
     
     
       30. The communication apparatus of claim 27, wherein the one of the SC-FDMA symbols is transmitted from a single antenna of the transmitter. 
     
     
       31. A communication device for a transmitter, the communication device comprising:
 a circuitry configured to:
 cause the transmitter to generate a first stream and a second stream; 
 cause the transmitter to perform first channel coding on the first stream to generate a first channel coded stream and perform second channel coding on the second stream to generate a second channel coded stream, wherein the first channel coding and the second channel coding are performed according to different coding schemes; 
 cause the transmitter to map the first and second channel coded streams to modulation symbols, wherein different channel coded streams are mapped to different modulation symbols; 
 cause the transmitter to generate single carrier frequency division multiple access (SC-FDMA) symbols from the modulation symbols, one of the SC-FDMA symbols being generated by using at least a part of the modulation symbols from the first channel coded stream and a part of the modulation symbols from the second channel coded stream; and 
 cause the transmitter to transmit the SC-FDMA symbols to a receiver. 
   
     
     
       32. The communication device of claim 31, wherein the circuitry is configured to, when generating the SC-FDMA symbols:
 cause the transmitter to map the modulation symbols to subcarriers; and   cause the transmitter to generate the SC-FDMA symbols from the subcarriers.   
     
     
       33. The communication device of claim 31, wherein a coding rate of the first channel coding is different from a coding rate of the second channel coding. 
     
     
       34. The communication device of claim 31, wherein the circuitry is further configured to cause the transmitter to receive feedback information from the receiver; and
 determine coding rates of the first channel coding and the second channel coding based on the feedback information.   
     
     
       35. The communication device of claim 31, wherein the one of the SC-FDMA symbols is transmitted from a single antenna.